Is the indexing approach in its current form a sustainable model for people and the planet in the long term? Who doesn’t like cheap stuff that works well? Consider index funds. First, a refresher: A market index is a hypothetical portfolio of investment holdings that represents a segment of the financial market; think S&P 500, Nasdaq Composite or Dow Jones Industrial Average, a widely used trio of indices among myriad others. An index fund is a mutual fund or exchange-traded fund (ETF) with a portfolio of holdings constructed to track a market index. They’re inexpensive,…